to the Chapter 21 - Oxyacetylene Cutting
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Transcript to the Chapter 21 - Oxyacetylene Cutting
Oxyacetylene Cutting
After completing this chapter, you will be able to:
◦ Demonstrate the proper and safe method of setting up
cylinders, regulators, hoses, and the cutting torch
◦ Demonstrate how to maintain a cutting tip and torch
◦ Demonstrate how to light a torch, adjust it, and make a
cut
◦ Describe a good oxyacetylene cut
◦ Discuss safety procedures to be followed when oxyfuel
cutting
Chapter #21 – Oxyacetylene Cutting
Primary cutting process in oxyfuel gas cutting
(OFC)
◦ Uses heat from oxygen fuel gas flame
Raises metal temperature to kindling temperature
High-pressure stream of oxygen is directed onto the metal,
causing it to be cut (rapidly oxidized)
◦ Processes are identified by fuel type mixed with oxygen
to produce the preheat flame
Chapter #21 – Oxyacetylene Cutting
Table 21-1 Fuel Gases
Used for Flame Cutting
A
B
FIGURE 21-1 (A) Oxyacetylene
portable cutting rig mounted on a
handcart for use in a shop area.
(B) Oxyacetylene setup mounted on a
trailer for use outside of a shop.
Larry Jeffus
Chapter #21 – Oxyacetylene Cutting
Oxyfuel gas cutting
◦ Used to cut iron base alloys (ferrous metals)
◦ Low carbon steels (up to 0.3% carbon)
Easy to cut
◦ High nickel steels, cast iron, and stainless steel
Considered uncuttable with OFC-A
◦ Nonferrous metals (e.g., brass, copper, and
aluminum)
Cannot be cut by oxyacetylene cutting
Chapter #21 – Oxyacetylene Cutting
Chapter #21 – Oxyacetylene Cutting
Chapter #21 – Oxyacetylene Cutting
Chapter #21 – Oxyacetylene Cutting
1) GOGGLES (shade 4-6)
2) GLOVES
3) PROTECTIVE CLOTHING
Chapter #21 – Oxyacetylene Cutting
1) Working area must be clear of unnecessary items
2) Protect yourself and others from flying sparks
3) Support and balance the metal being cut
4) Clear space underneath the cut
5) Use proper technique in starting a cut
Chapter #21 – Oxyacetylene Cutting
Oxyacetylene hand torch
◦ Most common oxyfuel gas cutting torch
Most cutting tips are made of copper alloy, but some tips
are chrome
FIGURE 21-2 Oxyfuel cutting torch.
Thermadyne Industries, Inc
Chapter #21 – Oxyacetylene Cutting
FIGURE 21-4 A mixing
chamber located in the tip.
American Welding Society
FIGURE 21-5 Injector
mixing torch.
American Welding Society
Chapter #21 – Oxyacetylene Cutting
FIGURE 21-7 Different manufacturers have
differently designed cutting torch tip seats.
Larry Jeffus
Chapter #21 – Oxyacetylene Cutting
Other Gases
Acetylene
THE CUTTING
TIP
Preheat
Flame Holes
Cutting
Oxygen Hole
Chapter #21 – Oxyacetylene Cutting
Exactly like setting up oxyfuel welding
equipment
◦ Except for adjustment of gas pressures
Refer to Chapter #21 of the text
Greater detail and practice will take place in shop
Chapter #21 – Oxyacetylene Cutting
Proper alignment of preheat holes will speed
up and improve the cut
FIGURE 21-19 Tip alignment for
a square cut. American Welding Society
FIGURE 21-20 Tip alignment
for a bevel cut. American Welding Society
Chapter #21 – Oxyacetylene Cutting
Laying out a line
◦ Done with soapstone or a chalk line
◦ Scribe or a punch can be used
FIGURE 21-22 Holding the
punch slightly above the surface
allows the punch to be struck
rapidly and moved along a line
to mark it for cutting.
Larry Jeffus
Chapter #21 – Oxyacetylene Cutting
Tips size selection:
◦ Designated by manufacturer numbering system
◦ Refer to manufacturer’s recommendation chart
◦ Size needed is determine by “material thickness”
◦ Pressure are then selected from chart
Chapter #21 – Oxyacetylene Cutting
Table 21-6 Cutting Pressure and Tip Size
Chapter #21 – Oxyacetylene Cutting
Oxyfuel gas cutting torch
◦ Metal cut rapidly oxidizes or burns
High-pressure stream of oxygen is directed on metal
preheated above kindling point
◦ Burning away of metal is a chemical reaction with iron
(Fe) and oxygen (O)
Oxygen forms an iron oxide
Heat is produced by metal as it burns
Chapter #21 – Oxyacetylene Cutting
THE WELDING TORCH OXYGEN VALVE MUST BE
WIDE OPEN
Chapter #21 – Oxyacetylene Cutting
THE HIGHER OXYGEN PRESSURE WILL CAUSE THE
OXYGEN TO BACK UP THE ACETYLENE HOSE,
CAUSING A HIGHLY EXPLOSIVE GAS TO COLLECT
IN THE ACETYLENE HOSE
Chapter #21 – Oxyacetylene Cutting
PRESS THE CUTTING OXYGEN VALVE
Chapter #21 – Oxyacetylene Cutting
Chapter #21 – Oxyacetylene Cutting
THE SPACE LEFT WHEN THE METAL IS CUT
Chapter #21 – Oxyacetylene Cutting
THE THICKNESS OR DISTANCE OF THE BEVEL
1.4 “
1”
1”
Chapter #21 – Oxyacetylene Cutting
MAKE A SMALL GOUGE WITH A COLD CHISEL,
HACK SAW OR ZIP CUT
Chapter #21 – Oxyacetylene Cutting
Oxyacetylene torch
◦ Indispensable tool
Speedy
Accurate
Saves time
FIGURE 21-92 Nuts and bolts on this rusty
plow could not be taken off without a torch.
Larry Jeffus
Chapter #21 – Oxyacetylene Cutting
Next set of slides deal with flame cutting
technique
Review if time permits
Chapter #21 – Oxyacetylene Cutting
Allow better control and even cutting
FIGURE 21-38 Using angle irons to aid in making cuts.
© Cengage Learning 2012
Chapter #21 – Oxyacetylene Cutting
Easier if one side of the metal is scrap
◦ Cut is turned out a short distance into the scrap side
No side is scrap
◦ Forward movement should be stopped before
releasing cutting lever
FIGURE 21-40 Turning out into
the scrap to make stopping and
starting points smoother.
© Cengage Learning 2012
Chapter #21 – Oxyacetylene Cutting
Burning a hole in the plate
FIGURE 21-59 Sequence for piercing a plate.
© Cengage Learning 2012
Chapter #21 – Oxyacetylene Cutting
FIGURE 21-83 Small diameter pipe
can be cut without changing the angle
of the torch. After the top is cut, roll
the pipe to cut the bottom.
© Cengage Learning 2012
FIGURE 21-84 On large diameter
pipe, the torch is turned to keep it at
a right angle to the pipe. The pipe
should be cut as far as possible
before stopping and turning it.
© Cengage Learning 2012
Chapter #21 – Oxyacetylene Cutting
THE CUT WILL BE CLEAN AND FREE OF SLAG
Chapter #21 – Oxyacetylene Cutting
THE KERF WILL HAVE A ROUNDED TOP EDGE AND
SLAG WILL ADHERE TO THE BOTTOM OF THE CUT
Chapter #21 – Oxyacetylene Cutting
Chapter #21 – Oxyacetylene Cutting
NOT ENOUGH PREHEAT WAS USED
Chapter #21 – Oxyacetylene Cutting